System and method for bracketing and removing tissue

ABSTRACT

A system and method for bracketing a tissue volume ( 22 ) and later locating the bracketed tissue volume. The system includes a plurality of markers ( 30 ) and a probe ( 32 ) and detector ( 34 ) for use in locating the markers by providing information usable by a surgeon that is representative of changes in proximity between the probe and the plurality of markers. The markers have various detection characteristics, e.g., they transmit gamma rays, that are detectable by an associated probe and detector. The tissue volume is removed by manipulating a cutting tool based on the proximity information provided by the detector which can be used by the surgeon to define the boundary of the tissue volume. A two-part cutting tool ( 200 ) is provided for removing the tissue volume, and a tissue anchor ( 300 ) is provided for stabilizing the tissue during removal. The system and method of the invention are particularly useful in bracketing and then removing a tissue volume from amorphous, pliable tissue such as breast tissue.

TECHNICAL FIELD

[0001] The present invention relates to a system for and method ofbracketing a tissue volume containing a tissue mass, e.g., anon-palpable breast tumor, using markers to define the boundary of thetissue volume and a probe and detector to locate the markers. Thepresent invention also pertains to a method of removing the bracketedtissue, a circular cutting tool for removing tissue in connection withthis and other methods, and a tissue anchor for reducing mobility oftissue during tissue removal procedures.

BACKGROUND

[0002] A current technique for performing an excisional biopsy of anon-palpable breast lesion that has been identified by mammogram orother method involves placement of a needle or guide wire (e.g., a“Kopanz wire”), with or without blue dye, to guide the surgeon to thelesion. The tip of the needle is generally placed directly in or asclose as possible to the lesion. When larger or more complex lesions areencountered, two or more guide wires are sometimes placed at each edgeof the lesion. The entry point of the needle through the skin of thebreast is usually several centimeters from the lesion due to thelogistics of needle placement. The surgeon does not cut along the shaftof the needle from the skin because the distance is too great. Instead,the surgeon must estimate where in the breast the lesion is located bymaking reference to the location of the needle.

[0003] This technique is not optimal. Due to the amorphous and highlypliable nature of certain tissue, e.g., breast tissue, it can bedifficult to properly define the margins of tissue to be removed, bothduring and after insertion of the needle(s). Also, it is often difficultfor the surgeon to detect the exact depth of the lesion based on theplacement of the needles. For these reasons it is not uncommon that thebiopsied tissue does not contain the mammographically positive specimen.In other cases, as a result of the difficulty of estimating the properlocation of the boundaries of the volume of tissue to be removed, thelesion ends up being eccentrically positioned within the volume oftissue excised. This calls into question the adequacy of the margin ofnormal tissue surrounding the lesion. In still other cases, more normaltissue is removed than is required, which is disadvantageous in this eraof tissue-conserving therapies.

[0004] In other fields of surgery it is known to target portions of ahuman body using various devices, and then refer to such devices inconnection with the removal or treatment of such portions. For example,U.S. Pat. No. 5,630,431 to Taylor (the “'431 patent”) describes asurgical manipulator that is controlled, in part, by informationreceived from beacons that are positioned proximate to a region of ahuman body to be treated. As another example, U.S. Pat. No. 5,397,329 toAllen (the “'329 patent”) describes fiducial implants for a human bodythat are detectable by an imaging system. The fiducial implants areimplanted beneath the skin and are spaced sufficiently from one anotherto define a plane that is detectable by the imaging system and is usedin connection with creation of images of a body portion of interest.These images are then used, for instance, in eliminating a tumor bylaser beam.

[0005] Unfortunately, the devices described in the '431 and '329 patentsare vastly more complex, and hence expensive, than is appropriate formany surgical procedures, particularly with the emphasis on costcontainment in managed health care. Furthermore, due to the amorphous,pliable nature of certain tissue, the systems of the '431 and '329patents cannot be used effectively. Systems of the type described in the'431 and '329 patents require that the devices (e.g., beacons orfiducial implants) defining the body portions of interest besubstantially fixed relative to one another and relative to such bodyportions. These systems generally function effectively when the devicesdefining the body portion of interest are inserted in bone, e.g., in askull in connection with brain surgery or treatment, but are notbelieved to operate as intended when the devices are inserted inamorphous, pliable tissue.

[0006] Breast lesions are typically excised with a scalpel manipulateddirectly by the surgeon. With the current emphasis on breast conservingsurgical therapies, the above-described procedure for removing a breastlesion is typically performed through a narrow opening in the skincreated by slitting and then pulling apart the skin. It tends to bedifficult to manipulate the scalpel within this opening so as to removethe desired volume of tissue. The amorphous, pliable nature of breasttissue exacerbates removal of such tissue inasmuch as application offorce to the scalpel causes movement of the breast tissue relative tothe opening in the skin.

[0007] Circular cutting tools are not widely used in surgery. Recently,however, U.S. Surgical Corporation of Norwalk, Conn., introduced arelatively small diameter, e.g., 5-20 mm, circular cutting toolidentified by the trademark ABBI for removing a cylinder of breasttissue for biopsy purposes. The ABBI tool includes an oscillating,motorized, circular cutting blade that incises the breast tissue. Whileuse of the ABBI tool is believed to be a relatively effective way toperform a core biopsys of breast tissue, it is not apparently designedto remove cylinders of tissue having a diameter much in excess of about20 mm. As such, it is not adapted for use in surgeries involving theremoval of relatively large tissue portions in a single cuttingsequence. In addition, the ABBI tool's effectiveness in therapeutic,rather than diagnostic, surgeries has not been confirmed.

[0008] Detectors are used to locate organs or other portions of the bodythat have taken up a radioactive material, e.g., an antibody labeledwith a radioactive material. For example, the gamma ray probe describedin U.S. Pat. Nos. 5,170,055 and 5,246,005, both to Carroll et al., andsold by Care Wise Medical Products Corporation, Morgan Hill, Calif., andidentified by the trademark C-TRAK, provides an audio output signal, thepitch of which varies with changes in relative proximity between theprobe and a body portion that has taken up an antibody labeled with agamma ray producing material, e.g., technetium 99. Once the body portionis detected, it is removed by known surgical techniques.

[0009] Even with the systems and techniques described above, it remainsdifficult for a surgeon to remove a tissue mass in amorphous, pliabletissue, such as breast tissue, so as to ensure the entire tissue mass isremoved while at the same time removing only minimal portions ofadjacent tissue. As a result, more unaffected tissue surrounding thetargeted tissue mass is typically removed than is desired.

SUMMARY

[0010] One aspect of the present invention is a system for bracketing atissue volume. The system includes a plurality of markers, each of whichhas a maximum dimension of no more than 5 mm, as measured along any axisextending through the marker. In addition, the system includes a probeand a detector connected to the probe that provides information when theprobe is proximate to one of the plurality of markers.

[0011] Another aspect of the present invention is a surgical marker thatincludes a quantity of colored dye and a capsule encasing the quantityof colored dye. One or both of the dye and capsule are readily imagableby at least one of ultrasonic, magnetic resonance and X-ray energy.

[0012] Yet another aspect of the present invention is a cutting toolthat includes a first portion and a second portion. The first portionincludes a first blade having a first edge with a first curvedconfiguration and a first connector. The second portion includes asecond blade having a second edge. The second edge has a second curvedconfiguration that is designed so that when the second blade ispositioned in operative engagement with the first blade, the first edgeand the second edge form a substantially continuous cutting edge. Inaddition the second portion includes a second connector positioned anddesigned to releasably engage the first collector so as to releasablysecure the first and second blades in operative engagement.

[0013] Still another aspect of the present invention is a tissue anchorfor reducing mobility of tissue during surgical or other procedures. Thetissue anchor includes an elongate tube having a central bore, a distalend and a proximal end. The tube comprises at least one apertureadjacent the distal end. The tissue anchor also has an elongate memberwith a portion sized for receipt and axial movement in the central borebetween a first position and a second position. The portion has a distalend and the elongate member includes at least one anchor member attachedto the portion adjacent the distal end. In addition, the at least oneanchor member is sized and positioned so that when the portion is in thefirst position the at least one anchor member is at least partiallyreceived in the elongate tube and when the portion is in the secondposition the at least one anchor member projects through the at leastone aperture.

[0014] Yet another aspect of the present invention is a method ofremoving a tissue volume from a tissue portion using a plurality ofmarkers. The method comprising the steps of (i) positioning a pluralityof markers so as to define a boundary of the tissue volume, (ii)detecting the location of a first one of the plurality of markers, and(iii) incising portions of the tissue portion adjacent the first one ofthe plurality of markers substantially along the boundary adjacent thelocation.

[0015] Still another aspect of the present invention is a method ofbracketing a tissue mass in a piece of tissue using a plurality ofmarkers. The method comprising the steps: (i) generating an image of thetissue mass, and (ii) referring to the image of the tissue mass,positioning the plurality of markers in the piece of tissue so as todefine a boundary of a tissue volume that includes the tissue mass.

[0016] Other aspects of the invention are described in the followingdetailed description of the invention, in the claims and in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is an idealized perspective view of a tissue mass andsurrounding tissue volume that is bracketed by the markers of thepresent invention, with two markers being positioned on opposite ends ofeach of mutually orthogonal X, Y and Z axes intersecting the tissue massso as to define the boundary of the tissue volume, and with the probeand detector of the present invention being positioned adjacent thetissue volume;

[0018]FIG. 1a is a perspective view of the tissue mass illustrated inFIG. 1, with two markers being positioned on opposite ends of each ofmutually orthogonal X1, Y1 and Z axes and with two markers beingpositioned on opposite ends of mutually orthogonal X2 and Y2 axes whichare mutually orthogonal with respect to the Z axis and offset along withZ axis with respect to the X1 and Y1 axes;

[0019]FIG. 1b is a perspective view of the tissue volume illustrated inFIG. 1, with two markers being positioned on opposite ends of each of V,W, X and Y axes, all of which lie in a common plane and are mutuallyorthogonal with respect to a Z axis, all of these axes intersecting thetissue mass;

[0020]FIGS. 2a-2 g are schematic representations of various embodimentsof the markers of the present invention and their associated detectioncharacteristics;

[0021]FIG. 3a is a block diagram of the elements of one embodiment ofthe marker illustrated in FIG. 2c;

[0022]FIG. 3b is a block diagram of the RF exciter used with the markerillustrated in FIG. 3a;

[0023]FIG. 4 is a block diagram of the elements of one embodiment of themarker illustrated in FIG. 2e;

[0024]FIG. 5 is a block diagram of the RF exciter used with the markerillustrated in FIG. 4;

[0025]FIG. 6 is a perspective view of one embodiment of the markerillustrated in FIG. 2f, with details of internal construction beingillustrated in phantom view;

[0026]FIG. 7 is a block diagram of the probe and detector used with themarker illustrated in FIG. 2b;

[0027]FIG. 8 is a block diagram of the probe and detector used with themarker illustrated in FIG. 2c;

[0028]FIG. 9 is an exploded perspective view of the cutter of thepresent invention, with the two portions of the cutter being shown indisengaged, spaced relation;

[0029]FIG. 10 is a perspective view of the cutter illustrated in FIG. 9,with the two portions of the cutter being shown in engaged, cooperativerelation;

[0030]FIG. 11 is a front elevation view of the tissue anchor of thepresent invention, with the cannula and rod of the cutter being shown inbroken view to facilitate illustration;

[0031]FIG. 12 is an enlarged view of the tissue anchor in FIG. 11, withthe rod and cannula both being broken at first location and the rodalone being broken at a second location to facilitate illustration, alsowith the rod being shown in a retracted position relative to thecannula;

[0032]FIG. 13 is similar to FIG. 12, except that the rod is shown in theextended position relative to the cannula, with the anchor membersattached to the end of the rod being shown in an extended positionengaged in a portion of a tissue mass;

[0033]FIG. 14 is a top view of a breast of woman in a supine position,with a tissue mass being surrounded by markers of the present inventionso as to define the tissue volume to be removed, and with an incisionformed in the skin of the breast above the tissue volume;

[0034]FIG. 15 is a cross-sectional view of the breast of FIG. 14 takenalong line 15-15 in FIG. 14;

[0035]FIG. 16 is similar to FIG. 14, except that the skin adjacent theincision has been pulled apart to provide access to underlying breasttissue;

[0036]FIG. 17 is an enlarged view of the incision of FIG. 16, with thetissue anchor illustrated in FIGS. 11-13 being positioned in the tissuemass, and the two portions of the cutter illustrated in FIGS. 9 and 10and probe of the present invention all being positioned adjacent thesurgical cavity;

[0037]FIG. 18 is similar to FIG. 15, except that an incision has beenformed in the skin of the breast and has been retracted to provideaccess to the underlying tissue mass to be removed and the tissue anchorhas been positioned above the breast;

[0038]FIG. 19 is an enlarged view of the portion of the breastillustrated in FIG. 18 containing the tissue mass to be removed, withthe tissue anchor being positioned in the tissue mass in the extendedposition so that the anchor members of the tissue anchor engage thetissue mass;

[0039]FIG. 20 is similar to FIG. 17, except that the two portions of thecutter are illustrated in engaged, cooperative relationship and arepositioned under the skin in contact with the tissue volume to beremoved;

[0040]FIG. 21 is similar to FIG. 18, except that the tissue cutter isillustrated surrounding the tissue anchor and in cutting engagement withthe tissue volume to be removed; and

[0041]FIG. 22 is similar to FIG. 21, except that the tissue volume hasbeen completely removed from the breast and is illustrated immediatelyabove the surgical opening in engagement with the tissue anchor andcutter.

DETAILED DESCRIPTION

[0042] Referring to FIG. 1, the present invention is a system 20 fordefining the boundaries of, i.e., bracketing, a tissue volume 22 in atissue portion 24. Typically, tissue volume 22 will include a tissuemass 26, e.g., a breast lesion, that is targeted for removal and atissue margin 28 of unaffected tissue surrounding the tissue mass. Aftertissue volume 22 is bracketed, system 20 can be used to locate thedefined boundaries of the tissue volume, e.g., in connection with thesurgical removal of tissue mass 26.

[0043] As described in more detail below, the present invention is alsodirected to a method of bracketing tissue volume 22 using system 20, anda method of removing tissue volume 22 using system 20. These methods canbe advantageously, although not necessarily, accomplished with otheraspects of the present invention, i.e., cutting tool 200 (FIGS. 9 and10) and tissue anchor 300 (FIGS. 11-13), both described below.

[0044] System 20 comprises a plurality of markers 30, a probe 32 and adetector 34 connected to the probe. As described in more detail below,markers 30 are implanted in tissue portion 24 under the guidance of aconventional imaging system not forming part of the present invention,so as to bracket tissue volume 22. Such imaging systems may includeultrasound, magnetic resonance imaging (“MRI”), computer-aidedtomography (“CAT”) scan, and X-ray systems. Markers 30 are imagable withthe imaging energy generated by the imaging system. For example, if anultrasound imaging system is used to implant markers 30, the latter areconfigured and made from a material that strongly reflects ultrasoundenergy. Materials that are imagable with the energy generated by suchsystems are well known to those skilled in the art, and so are notdescribed in detail here. Following implantation of markers 30, probe 32and detector 34 are used to locate the markers, as described in moredetail below.

[0045] The terms “probe 32” and “detector 34” are used genericallyherein to refer to all embodiments of the probe and detector describedbelow. Specific embodiments of the probe 32 and detector 34 areidentified using a prime notation described below, i.e., probe 32′ ordetector 34″.

[0046] Markers

[0047] Preferably, markers 30 are biologically inert and are relativelysmall so that they interfere as little as possible with the removal orother treatment of tissue volume 22. Markers 30 may have differentgeometric configurations, e.g., spherical, disk-like, cylindrical.However, it is preferred that the greatest dimension of a marker 30, asmeasured along any axis extending through the marker from one surface toan opposite surface, is not more than about 5 mm. Ideally, markers 30are even smaller, i.e., the greatest dimension is about 1-2 mm.

[0048] In addition, markers 30 each have a detection characteristic toenable detection by probe 32 and detector 34. The detectioncharacteristics of the various embodiments of markers 30 can becharacterized as active or passive. In the active category, thedetection characteristic of a first embodiment of marker 30, illustratedin FIG. 2a as marker 30 a, is gamma rays 40. In this regard, marker 30 amay include materials such as technetium 99, cobalt isotopes or iodineisotopes. Such materials may be obtained from DuPont of Billerica,Massachusetts. Preferably, each marker 30 a generates gamma rays 40having a field strength in the range of 1-100 microCurries.

[0049] Also in the active category, in a second embodiment of marker 30,illustrated in FIG. 2b as marker 30 b, the detection characteristic ismagnetic field 42. Markers 30 b of the second embodiment thus containferromagnetic materials in which a magnetic field can be induced, oralternatively are permanently magnetized and so have an associatedpermanent magnetic field. In FIG. 2b, magnetic field 42 represents boththe induced and inherent magnetic fields. Strong permanent magnets, suchas those made from Samarium-Cobalt, are typically preferred for markers30 b.

[0050] Referring to FIG. 2c, in a third embodiment, again in the activecategory, marker 30 c emits radio frequency (“RF”) signal 44 in responseto a triggering signal 46. Various energy sources may be used fortriggering signal 46, including a magnetic field, ultrasound or radiofrequency energy. In this latter case, marker 30 c is preferablydesigned to receive triggering signal 46 which has a first RFwavelength, and in response thereto, emit signal 44 of a second RFwavelength. In the simplest case, no data, other than the specific radiofrequency itself, is carried in signal 44. Alternatively, markers 30 cmay all transmit signal 44 at a single frequency, with data uniquelyidentifying each marker being carried in signal 44 emitted by eachmarker.

[0051] A suitable marker 30 c is illustrated in FIG. 3a. This marker 30c includes a transmit/receive antenna 52 for receiving an RF signal at afirst frequency and transmitting an RF signal at a second frequency.Also included is a power detect/regulate circuit 54 connected to antenna52 that detects the presence of, and regulates, the RF signal receivedby the antenna. The regulated RF signal is provided from circuit 54 todrive radio frequency generator 56 which generates an RF signal at asecond frequency. As discussed in more detail below, when multiplemarkers 30 c are used together in a given bracketing procedure,preferably each marker transmits RF signals at a second frequency whichis unique to the marker. The RF signal generated by radio frequencygenerator 56 is then provided to antenna 52 where it is transmitted asan RF signal. While it is preferred the frequency of RF signal 44transmitted from markers 30 c be unique for each marker 30 c used in agiven bracketing procedure, the frequency of the received RF signal 46is preferably common with respect to all of the markers 30 c used in thebracketing procedure.

[0052] Referring to FIG. 3b, an RF exciter device 60 for generating RFsignal 46 is illustrated. RF exciter 60 includes a radio frequencygenerator 62 for generating RF signal 46 at a predetermined frequencyand an RF amplifier 64 for amplifying the output from the radiofrequency generator. The sensitivity of amplifier 64 may be controlledusing gain adjustment 62 coupled to the amplifier. The output of RFamplifier 64 is provided to transmit antenna 68 which transmits RFsignal 46. Transmit antenna 68 of RF exciter 60 is preferably placed inrelatively close proximity to marker 30 c, with appropriate gainadjustment of RF amplifier 64 being achieved by control gain adjustment66 until a suitable return signal is absorbed from detector 34″,discussed below and illustrated in FIG. 8.

[0053] In a fourth embodiment, again in the active category, marker 30d, illustrated in FIG. 2d, continuously emits signal 44 at specificfrequencies in the radio frequency spectrum. The marker 30 c illustratedin FIG. 3a and described above can be satisfactorily employed as marker30 d by adding a battery (not shown) in place of power detector portionof circuit 54 of marker 30 c. RF exciter 60 is not required inconnection with marker 30 d, insofar as the battery generates the energyused by the marker in producing RF signal 44.

[0054] As a fifth embodiment in the active category, marker 30 e,illustrated in FIG. 2e, is designed to vibrate following implantation.This vibration is a detection characteristic that is chosen to enhanceimage contrast when marker 30 is intended to be detected using a probe32 and detector 34 that perform ultrasound imaging. More specifically,incoming ultrasound signal 74 is reflected off marker 30 e as reflectedultrasound signal 76, with a Doppler shift component being added to thereflected signal due to the vibration of the marker to enhanceimagability of the marker. The vibration frequency of marker 30 e willvary depending upon the frequency of ultrasound energy generated byprobe 32, but is preferably lower than the frequency of incomingultrasound signal 74 which is typically 7.5 MHz, i.e., the vibrationfrequency is preferably in the 50 Hz to 50 KHz range.

[0055] A suitable marker 30 e that achieves the functionality describedabove is illustrated in FIG. 4. This marker 30 e includes an antenna 80for receiving an RF signal that provides the energy driving the marker.A power detection and regulation circuit 82 is connected to antenna 80for detecting when the antenna is receiving an RF signal and forregulating the signal for use by oscillator and waveform generatorcircuit 84 connected to circuit 82. Circuit 84 converts the regulated RFsignal received from circuit 82 into an oscillating electrical signal,preferably in the audio frequency range (i.e., 20 Hz-20 kHz), having awaveform that is optimized to drive piezoelectric device 86 connected tocircuit 84. Piezo-electric device 86 is a conventional piezo-electricdevice of the type that converts an oscillating electrical input signalinto mechanical oscillations. Piezoelectric device 86 is attached viasupport 88 to outer housing 90 of marker 30 e. Housing 90 is designed toresonate at the mechanical oscillation frequency of piezo-electricdevice 86.

[0056] Referring to FIG. 5, an RF coupled acoustic exciter 92 isprovided for generating the RF signal received by antenna 80 of marker30 e. Exciter 92 includes a radio frequency generator 94 for generatingan RF signal. RF amp 96, with a gain adjustment 98 connected thereto, isprovided for receiving and amplifying the output signal from generator94. A transmit antenna 100 is provided for receiving the output of amp96 and transmitting the RF signal used to drive marker 30 e. In use,gain 98 of amp 96 is adjusted to amplify the RF signal produced bygenerator 94 such that marker 30 e is caused to mechanically oscillateso it is most clearly observable by the ultrasound imaging system (notshown) used in conjunction with marker 30 e.

[0057] As those skilled in the art will appreciate, other circuitconfigurations may be used in marker 30 e to cause piezo-electric device86 to vibrate. For example, a frequency divider circuit (not shown) maybe used in place of oscillator/waveform generator circuit 84. With suchalternative, exciter 92 is modified to include a variable frequencyoscillator (not shown) in place of radio frequency generator 94.

[0058] In the passive category, the detection characteristic in a sixthembodiment of marker 30, illustrated as marker 30 f in FIG. 2f, isopacity to incoming ultrasound signal 74. That is, marker 30 f reflectsincoming sound energy sufficiently to create a strong image in reflectedsignal 76 so as to enhance imagability using a conventional ultrasoundimaging system. In many cases, it will be advantageous to incorporatethe detection characteristics of marker 30 f in marker 30 e.

[0059] While those skilled in the art are familiar with materials andconfigurations that can be used for marker 30 f, one suitable marker 30f is illustrated in FIG. 6. This marker 30 f includes plate 102, plate104 and plate 106, all of which are preferably arranged in mutuallyorthogonal relationship. It is preferred that each of the plates 102-106has a square configuration and the length of each edge of the plates,e.g., the length of edge 108 of plate 104, is preferably about twice thewavelength of incoming ultrasound signal 74. For example, when incomingultrasound signal 74 has a wavelength of 7.5 MHz, edge 108 has a lengthof about 2 mm. Plates 102-106 are made from a material that stronglyreflects ultrasound energy, e.g., aluminum, and typically have athickness in the range of 10-100μm. Plates 102-106 ideally are enclosedin a biologically non-reactive casing 110. The latter is preferably madefrom a material that does not have strong ultrasound reflectioncharacteristics, e.g., a soft polymer.

[0060] Also in the passive category, marker 30 g of the seventhembodiment, illustrated in FIG. 2g, comprises a capsule (not shown)filled with a colored dye 78, e.g., a vital dye. Either or both thecapsule and dye 78 of marker 30 g are made from a material that isimagable by the imaging system, e.g., ultrasound, used to implant themarkers, as described in more detail below. The capsule is made fromgelatin or other suitable material that is selected to be sufficientlytough to withstand insertion into tissue volume 22, but is relativelyeasily cut by the cutting tool used to remove the tissue volume, e.g., aconventional surgical scalpel or cutting tool 200 described below.Marker 30 g provides a visual guide as to its location by releasingcolored dye 78 when severed by a surgical cutting tool. In this regard,probe 32 and detector 34 are not used in connection with marker 30 g.

[0061] Markers 30 a, 30 b and 30 f may be made from a solid structurecontaining material having tile desired detection characteristic.Alternatively, markers 30 a, 30 b and 30 f may be made from a capsulefilled with a dye, such as is used for marker 30 g, containing materialhaving the desired detection characteristic. As another alternative, allembodiments of markers 30 may include a dye contained in an outercapsule having the requisite toughness and severability characteristicsnoted above.

[0062] Probe and Detector

[0063] The design and function of probe 32 and detector 34 depend uponthe embodiment of marker 30 used. However, for all embodiments of marker30 (except marker 30 g), detector 34 is designed to provide humanlyrecognizable information when probe 32 is positioned within a selectedproximity, e.g., 1-5 cm, of a given marker. This information may takeone of a variety of forms, including a burst of humanly perceivablesound, constant or intermittent illumination of a light, movement of aneedle on a dial, a short burst of air, change of data in a visualdisplay, increased image brightness or contrast (in the case whendetector 34 is an ultrasound imaging system, as discussed below) orother humanly perceivable proximity information. In this regard detector34 may include a dial 112, light 114, speaker 116, or other appropriatedevices for generating the selected form of humanly perceivableinformation.

[0064] Preferably, although not necessarily, detector 34 provideshumanly recognizable information that indicates changes in proximity ofprobe 32 to a given marker 30. Thus, rather than merely providing staticor threshold information that probe 32 is within a predetermined rangeof a given marker 30, detector 34 preferably provides proximityinformation having an attribute or characteristic that varies as afunction of changes in proximity of the probe relative to the marker.For example, if the proximity information is sound, the pitch is variedwith changes in proximity. Or, as another example, if the proximityinformation is light, the brightness of the light changes with changesin proximity.

[0065] A probe and detector that may be satisfactorily employed as probe32 and detector 34, respectively, when the latter is intended to detectmaker 30 a, is sold by Care Wise Medical Products Corporation of MorganHill, California, and is identified by the trademark C-TRAK. The C-TRAKprobe, which is described in U.S. Pat. Nos. 5,170,055 and 5,246,005 toCarroll et al., which are incorporated herein by reference, provides ahumanly audible sound, the pitch of which varies with changes inproximity of the probe to tissue labeled with gamma ray producingmaterial.

[0066] Referring to FIGS. 1, 2b and 7, when probe 32 and detector 34 areintended for use in detecting marker 30 b, which generates a magneticfield 42, probe 32′ and detector 34′ illustrated in FIG. 7 may besatisfactorily employed. Probe 32′ includes a conventional Hall effectsensor (not shown) that provides an output signal on line 120, thevoltage of which varies as a function of proximity of the probe to themagnetic field generated by a marker 30 b. Detector 34′ is connected toprobe 32′ via line 120, and includes an amplifier 122 connected to line120 for amplifying the signal from the Hall effect sensor in probe 32′.Amplifier 122 includes an offset adjustment 126 and a gain adjustment128. Offset adjustment 126 is provided to cancel the effects of anyambient magnetic fields, such as that of the earth. Gain adjustment 128is provided to control the overall sensitivity of detector 34′. Theamplified signal from amplifier 122 is delivered on line 124 to signalmeter 126, which may comprise a dial with a movable needle, an LED orother device for representing signal strength. Also connected to line124 is voltage controlled oscillator 128, the output of which isprovided to amplifier 130. The output of amplifier 130 drives speaker116. The frequency of the output signal from voltage controlledoscillator 128 varies as function of changes in voltage of the signaldelivered on line 124, which in turn causes the pitch of the soundproduced by speaker 116 to vary as a function of changes in the voltageof the signal on line 124. As those of ordinary skill in the art willappreciate, other devices for providing humanly recognizable informationrepresenting changing proximity, e.g., a light may be employed insteadof speaker 116.

[0067] Referring to FIGS. 1, 2c and 8, for markers 30 c and 30 d, whichgenerate radio frequency energy, probe 32″ and detector 34″ are providedfor use in detecting the markers. Probe 32″ includes a conventional coilantenna 140 for receiving an RF signal. Detector 34″ includes aselectable notch filter 142 connected to antenna 140 which permitstuning of the detector to the unique RF frequency of signal 44 emittedby markers 30 c or 30 d. A tuning knob or other user adjustablemechanism (neither shown) is attached to selectable notch filter 142 topermit a user to perform such tuning. The output of selectable notchfilter 142 is provided to RF amplifier 144, the overall sensitivity ofwhich may be controlled by gain adjustment 146 attached to theamplifier. The output of RF amplifier 144 is provided torectifier/integrator circuit 148 which rectifies and time filters thesignal. The output of rectifier/integrator circuit 148 is provided toanalog signal strength display 150 which provides a visual indication ofthe proximity of probe 32″ to marker 30 c. In addition, the output ofrectifier/integrator circuit 148 is provided to voltage oscillator 152which generates an output signal, the frequency of which varies as afunction of the voltage level of the signal provided byrectifier/integrator circuit 148. The output signal of the voltagecontrol oscillator 152 is amplified by audio amplifier 154, which inturn drives speaker 116. Accordingly, the pitch of the sound generatedby speaker 116 varies as a function of the strength of the RF signalreceived by probe 32″, and hence as a function of the proximity of probe32″ to markers 30 c or 30 d.

[0068] A suitable probe 32 and detector 34 for use with the markers 30 eand 30 f is the ultrasound imaging system available from DornierSurgical Products, Inc., Phoenix, Ariz., is identified by the namePerforma, and generates ultrasound energy having a frequency of 7.5 MHZ.

[0069] Cutter

[0070] As described in more detail below in connection with thedescription of methods of using system 20, tissue volume 22 that isbracketed with markers 30 may be surgically removed using one of avariety of tools. Referring to FIGS. 9 and 10, one of these tools iscutter 200.

[0071] Cutter 200 includes portions 202 and 204. Portion 202 has acurved plate 206 that preferably traverses an arc of 180°, as measuredbetween ends 208 and 210. Plate 206 includes a bottom edge 212 that ispreferably sharpened. Plate 206 also includes a top edge 214 that istypically blunt.

[0072] Portion 202 also includes a handle 220 having an elongate centralsection 222 and a transverse section 224 attached to an upper end of thecentral section. Preferably, transverse section 224 extends normally tothe long axis of central section 222, although other non-orthogonalrelationships are encompassed by the present invention. Handle 220 isattached to curved plate 206 by several, e.g., three, spokes 226 thatare attached to the plate at spaced locations and extend radiallyinwardly from the plate toward the bottom end of central section 222where they are also attached. Handle 220 also includes apertures 228 and230. As illustrated in FIGS. 9 and 10, apertures 228 and 230 arepositioned at the upper end of handle 220. However, it is to beappreciated that apertures 228 and 230 may be positioned at otherlocations in central section, and, as an alternative one and more thantwo apertures may be used. Handle central section 222 also includes anelongate groove 232 extending the length of the central section.

[0073] Portion 204 is nearly identical to portion 202. In this regard,portion 204 includes a curved plate 236 that traverses an arc of 180°between ends 238 and 240, has a bottom edge 242 that is preferablysharpened, and has a top edge 244. Portion 204 also includes a handle250 having a central section 252 and a transverse section 254, withcentral section 252 and curved plate 236 being connected by spokes 256.Handle central section 252 includes an elongate groove 255 extending thelength of the central section. The placement of groove 255 on centralsection 252 is selected so that when portion 202 and 204 are positionedin operative engagement, as illustrated in FIG. 10 and described in moredetail below, groove 255 confronts groove 232 in central section 222,and together the grooves form a central bore extending the length ofcentral sections 222 and 252. The thickness of plate 236, as measuredbetween edges 242 and 244, is preferably the same as the thickness ofplate 236, as measured between edges 212 and 214. This thickness istypically in the range of 2 mm-25 mm.

[0074] Portion 204 differs from portion 202 in that it includesprojections 258 and 260 in place of apertures 228 and 230. Projections258 and 260 are sized and positioned to be snugly received in apertures228 and 230, respectively, when portions 202 and 204 are positioned inoperative engagement, as illustrated in FIG. 10. Transverse section 252is preferably positioned relative to central section 250 so that whenportions 202 and 204 are positioned in operative engagement, transversesection 252 extends in an opposite direction relative to transversesection 224.

[0075] When portions 202 and 204 are assembled to perform a cuttingoperation, they confront and engage one another, as illustrated in FIG.10. In this regard, the radii of curvature of curved plates 206 and 236are preferably substantially identical so that when end 210 contacts end238 and end 208 contacts end 240, as illustrated in FIG. 10, plates 206and 236 form a circular structure. In this engaged relationship, centralsections 222 and 250 contact one another, with a central rotational axis262 extending between the sections along their longitudinal axes. Alsoin this engaged relationship, apertures 228 and 230 receive projections258 and 260, respectively, which ensures a rotational force appliedabout axis 262 to one of transverse sections 224 and 252 is transmittedfrom one of portions 202 and 204 to the other.

[0076] In certain applications it may be desirable to modify theconstruction of, or even eliminate, handles 220 and 250 from cutter 200.When so modified, it is preferred that connectors or other engagementmechanisms be provided for releasably securing portion 202 in operativeengagement with portion 204, as illustrated in FIG. 10, so that bothportions rotate together when a rotational force is applied to one ofthe portions, as described in more detail below in connection with thediscussion of the operation of cutter 200. Such connectors or otherengagement mechanisms may be provided at ends 208, 210, 240 and 242,where spokes 226 join and spokes 256 join, or at other appropriatelocations.

[0077] Cutter 200 is preferably made from stainless steel. However,other materials including aluminum and certain plastics may be used inthe construction of cutter 200.

[0078] Tissue Anchor

[0079] Turning now to FIGS. 11-13, another aspect of the presentinvention is tissue anchor 300. The latter is designed to stabilizetissue mass 26 during surgical removal of the mass using system 20, asdescribed in more detail below.

[0080] Tissue anchor 300 includes a ring 302 sized to receive the thumbor finger of a user, and a rod 304. The latter includes a proximal end305, which is attached to ring 302, and a distal end 306. Rod 304includes an outwardly projecting pin 308 that serves as a stop, asdescribed below. Tissue anchor 300 also includes a plurality of, e.g.,four, anchor members 310 that are attached to rod 304 at or adjacent itsdistal end 306. Typically, anchor members 310 are attached to rod 304 soas to extend away from its distal end 306, as illustrated in FIGS. 12and 13. However, as an alternative design, anchor member 310 may beattached to rod 304 so as to extend away from distal end 306 towardproximal end 305 (not shown). Each anchor member 310 may terminate witha barb 312 (FIG. 13), if desired. Anchor members 310 preferably have acurved configuration when in an unbiased state, as illustrated in FIGS.11 and 13. Anchor members 310 are preferably made from spring steel,although other “memory” metal alloys made also be satisfactorily used.In certain applications it may be unnecessary to provide a curve inanchor member 310, i.e., the anchor member may be substantiallystraight.

[0081] Rod 304 preferably, although not necessarily, has a circularcross section. The outside diameter of rod 304 depends upon its intendedapplication, but is typically in the range of 0.3-10 mm, preferablyabout 1-2 mm. The length of rod 304, as measured between proximal end305 and distal end 306, also depends upon its desired application, buttypically ranges from 5-20 cm.

[0082] Tissue anchor 300 also includes a cannula 320 having a centralbore 322, a proximal end 324 and a pointed distal end 326. Central bore322 has an inside diameter that is sized to receive rod 304 with a closesliding fit. Cannula 320 has an outside diameter that is selected basedon the intended application but is typically in the range 0.5 mm-12 mm,preferably about 1-3 mm. Cannula 320 also includes an elongate slot 328that runs parallel to the long axis of the cannula and is sized toreceive pin 308 with a close sliding fit. The length of slot 328 issubstantially the same as the length of anchor members 310. Slot 328includes a pocket 329 at its end closest to distal end 326 of cannula320 that extends orthogonally to the long axis of the slot and is sizedto receive pin 308.

[0083] Cannula 320 also includes, a plurality of apertures 330 extendingthrough the wall of the cannula. Apertures 330 are positioned adjacentdistal end 326 of cannula 320 when anchor members 310 are attached torod 304 to extend away from distal end 306 as illustrated in FIGS. 12and 13. If anchor members 310 extend from distal end 306 toward proximalend 305 (not shown), then apertures 330 are moved toward the proximalend so that they are spaced from the proximal at least about the lengthof the anchor members. One aperture 330 is typically provided for eachanchor member 310. The lengths of anchor members 310, cannula 320, andslot 328 are together selected so that a small portion, e.g., about 1mm, of each anchor member 310 projects from its respective aperture 330when tissue anchor 300 is in the retracted position illustrated in FIG.12. In this position, pin 308 engages the end of slot 328 closest toproximal end 324. Anchor members 310 are sized in this manner to ensurethe anchor members remain positioned in their respective apertures 330when tissue anchor 300 is in the retracted position illustrated in FIG.12.

[0084] The lengths of anchor members 310, cannula 320, and slot 328 arealso together selected so that most, if not substantially the entire,length of the anchor members 310 projects from their respectiveapertures 330 when tissue anchor is in the extended position illustratedin FIGS. 11 and 13. In this position, pin 308 engages the end of slot328 closest to distal end 326.

[0085] The elements of tissue anchor 300 are preferably made fromstainless steel, a plastic such as polystyrene or polyurethane, or othermaterials suitable for the intended application of the tissue anchor (asdescribed in more detail below) known to those skilled in the art. Asnoted above, in many cases it is desirable to make anchor members 310from spring steel or a “memory” metal alloy.

[0086] Bracketing

[0087] Referring now to FIGS. 1, 14 and 15, markers 30 may be used tobracket (i.e., define the boundaries of) tissue volume 22 in a tissueportion 24 in accordance with the following method. In the followingdescription of the method of bracketing tissue volume 22, the latter iscontained in a human breast. However, it is to be appreciated thattissue volume 22 may be present in other organs and structures, e.g., aliver, or may constitute an entire organ or structure.

[0088] As the first step in bracketing tissue volume 22, a tissue mass26 of interest is identified through conventional imaging methods, e.g.,ultrasound, MRI, X-ray or CAT scan. Next, markers 30 are implanted intissue portion 24 surrounding tissue mass 26 and defining outerboundaries of tissue volume 22. The number of markers 30 used, and theplacement of the markers relative to tissue mass 26, will vary dependingupon the location of the tissue mass relative to other types of tissue,e.g., bone or muscle, surgeon preference, size and configuration of thetissue mass and the desired amount of tissue margin 28 (FIG. 1) beyondthe edge of tissue mass 26. However, in many applications, it isdesirable to use at least six markers 30 to bracket tissue volume 22,preferably two on each of axes X, Y and Z (see FIGS. 1, 14 and 15).Preferably the two markers 30 are positioned on each of axes X, Y and Zso as to lie on opposite boundaries of tissue volume 22.

[0089] For example, as illustrated in FIG. 1, marker 30, lies on the Zaxis at the upper surface of tissue volume 22, marker 302 lies on the Zaxis at the lower surface of the tissue volume, marker 303 lies on the Xaxis at a first location on the outer surface of the tissue volume,marker 304 lies on the X axis at a second location on the outer surfaceof the tissue volume diametrically opposite marker 303, marker 305 lieson the Y axis at a third location on the outer surface of the tissuevolume and marker 306 lies on the Y axis at a fourth location on theouter surface of the tissue volume diametrically opposite marker 305.

[0090] While it is preferred that axes X, Y and Z be mutuallyorthogonal, as illustrated, this is not mandatory and can be difficultto precisely implement in practice. However, it is generally preferablethat tissue volume 22 be completely surrounded by markers 30, i.e., thatthe tissue volume be defined in three dimensions by the markers. Onenotable exception to this preference is that the marker 30, such asmarker 30 ₂ show in FIGS. 1 and 15, positioned at the base of, i.e.,underneath, tissue volume 22 is not typically required when a differenttype of tissue, such as pectoral muscle 400 (FIG. 15) is located at ornear where the marker would be positioned. The illustration of marker302 in FIG. 15 is not inconsistent with this recommended placementregime for markers 30 because of the relatively great spacing between,the marker 302 and pectoral muscle 400. Similarly, when the marker 30,such as marker 30, shown in FIG. 1, to be positioned on top of tissuevolume 22 is near the skin overlying the tissue volume, such marker isnot typically required. Also, while the X, Y and Z axes are illustratedin FIG. 1 as intersecting at a common point centrally located withintissue mass 26, this is not required. For example, it may be desirableto offset the X and Y axes somewhat, as measured along the Z axis.Furthermore, in some cases it may be desirable to define tissue volume22 with markers 30 in only two dimensions or in only one dimension.

[0091] In some cases, it will be desirable to use more than two markers30 on X, Y and Z axes. Referring to FIG. 1a, in a first case, tenmarkers 30 are used, two on the Z axis, two on an axis X₁, two on anaxis X₂ that is offset along the Z axis with respect to axis X₁, two onan axis Y₁, and two on an axis Y₂ that is offset along the Z axis withrespect to axis Y₁. Referring to FIG. 1b, in a second case, ten markers30 are used, two on the X axis, two on the Y axis, two on the Z axis,two on the V axis which bisects the X and Y axes and two on the W axiswhich also bisects the X and Y axes, but at a different location. Othernumbers and relative placements of markers are also encompassed by thepresent invention.

[0092] Markers 30 are preferably spaced from tissue mass 26 so as todefine tissue volume 22 such that tissue margin 28 is large enough toensure none of the tissue mass lies outside the tissue volume. Thisprecise spacing will vary with the nature of the tissue mass 26, thesize of the tissue mass, surgeon preference and other factors. However,tissue margin 28, as measured outwardly along an axis extendingperpendicular to a surface location on tissue mass 26, is generallyabout 0.5 cm to 3 cm, and is preferably about 1 cm to 2 cm.

[0093] Markers 30 may be implanted in tissue portion 24 in a variety ofdifferent ways using a variety of different tools. In general, markers30 are implanted using a conventional imaging system (not shown) thatsimultaneously generates an image of tissue mass 26 and the markers. Byfrequently comparing the location of markers 30 to tissue mass 26 duringimplantation of the markers into tissue portion 24, based on imageinformation received from the imaging system, the markers may bepositioned so as to define tissue volume 22 in the manner describedabove. As noted above, markers 30 are made from a material that providesgood image contrast with respect to the imaging energy used.

[0094] It is preferable to at least partially immobilize tissue portion24 during implantation of markers 30. However, this is less criticalthan might be expected because by comparing the relative location of amarker 30 to tissue mass 26, the desired relative placement cantypically be achieved, even if tissue portion 24 is moving during markerimplantation.

[0095] Marker Implantation

[0096] Various techniques may be used to implant markers 30 in tissueportion 24. With reference to FIGS. 14 and 15, one approach is to insertmarkers 30 percutaneously through skin 402 overlying tissue portion 24using known needle pushers or implanters (neither shown) of the typeused to implant “seeds” of radioactive material for various cancertreatments. For example, needle pushers of the type sold by BestIndustries of Springfield, Va., may be satisfactorily employed. Theseneedle pushers include a central needle surrounded by an outer tubehaving an end plate or cup for supporting the radioactive “seed.”Following insertion of the needle pusher into the selected tissue mass,the radioactive “seed” is released by pressing the central needledownwardly relative to the surrounding outer tube, with the point of theneedle ejecting the “seed” from the end plate or cup of the outer tube.

[0097] To percutaneously insert marker 30 in accordance with this firstapproach, the marker is positioned on the end of the needle pusher (inplace of the radioactive “seed”), is forced through skin 402 and, usingfeedback from the imaging system, is guided to the region where it isdesired to implant the marker. Then the marker 30 is ejected from theneedle pusher by urging the central needle forwardly into the innertube.

[0098] A second approach for implanting markers 30 involves creating asmall, e.g., 5-10 mm, incision (not shown) in the skin 402 (see FIGS. 1and 14) overlying tissue portion 24. Next, a scalpel is inserted throughthe incision so as to form a slit in the underlying tissue portionextending to the position where it is desired to implant a maker 30.Then a marker 30 is inserted through the slit to such position using atweezers, needle pusher, trocar or other suitable tool. Other markers 30are implanted through separate incisions in skin 402 in similar mannerso as to bracket tissue volume 22.

[0099] Referring now to FIGS. 1 and 14-16, a third approach forimplanting markers 30 is to form a relative large, e.g., 1-3 cm,incision 404 (see FIG. 14) in skin 402 overlying tissue mass 26. Next,incision 404 is pulled open as illustrated in FIG. 16 Using retractorsor other conventional devices so as to form a relatively large openregion 406 above tissue mass 26. Markers 30 are then implanted intotissue portion 24 using either the first or second approaches describedabove.

[0100] Other approaches for implanting markers 30 so as to brackettissue mass 26 are also encompassed by the present invention. The speedand accuracy with which markers 30 may be implanted, and minimizingtrauma associated with implantation, are important objectives toconsider in selecting other approaches for implanting markers 30.

[0101] Marker Identification

[0102] Once tissue mass 26 has been bracketed in the manner describedabove, tissue volume 22 can be removed using either of two proceduresencompassed by the present invention. As described in more detail below,the first procedure involves identifying the boundaries of tissue volume22 using an embodiment of probe 32 and detector 34 that is appropriatefor the type of marker 30 used, as discussed above. Using informationfrom detector 34 regarding such boundaries, tissue volume 22 is thenremoved using a scalpel, cutter 200 or other tool, with tissue anchor300 preferably, but not necessarily, being used to stabilize the tissuevolume during removal.

[0103] The second procedure is similar to the first, except that tissueanchor 300 is not used.

[0104] For both the first and second procedures for removing tissuevolume 22, as the first step the surgeon typically identifies theboundaries of the tissue volume using system 20. This step is generallyneeded because in practice markers 30 will often be implanted by anotherdoctor, e.g., a radiologist, as a separate procedure. The boundaries oftissue volume 22 are identified by moving probe 32 in the general regionof the tissue volume and then monitoring the detection information(e.g., sound, light, dial movement, image clarity and the like) providedby detector 34. As noted above, detector 34 may provide this informationwhen probe 32 is moved within a predetermined proximity of a givenmarker 30, or may provide this information in a form that changes withchanges in proximity of the probe to the marker (e.g., a light getsbrighter as the probe is moved toward a marker and dimmer as it is movedaway).

[0105] The interaction between marker 30 and probe 32 and detector 34depends upon the detection characteristic of the marker. In the case ofmarker 30 a, which emits gamma rays 40 (FIG. 2a) on a continuous basis,a probe and detector of the type described in U.S. Pat. Nos. 5,170,055and 5,246,005 to Carroll et al. (the “C-TRAK probe”), as discussedabove, may be satisfactorily used to detect the markers. The C-TRAKprobe includes a radiation detector, e.g., a scintillation crystal,which provides an output signal that is believed to vary as a functionof the flux density of the gamma rays 40 emitted by marker 30 a. Changesin this output signal are then converted into humanly recognizabledetection information, e.g., sound, having a characteristic, i.e., pitchor tempo in the case of sound, that varies with changes in gamma rayflux density. By observing the location of probe 32 when the detectioninformation from detector 34 indicates the probe is closest to a givenmarker 30 a, the surgeon can mentally note where the marker is located.Repetition of this process will result in identification of the locationof all markers 30 a.

[0106] Referring to FIGS. 2b and 7, in the case of marker 30 b, whichgenerates a magnetic field 42, probe 32′ and detector 34′ are used todetect the marker. To locate a marker 30 b, the surgeon moves probe 32′in the general region of tissue volume 22, with the result that as theprobe approaches a given marker 30 b its Hall effect sensor (not shown)generates an output signal having a voltage that increases as the probeis moved toward the marker. Similarly the voltage of the output signaldecreases as probe 32′ is moved away from the marker 30 b. The outputsignal of probe 32′ is provide via line 120 to amplifier 122, whichamplifies the output signal from the probe. As discussed above, theamplified voltage signal from probe 32′ is displayed on signal meter 126and is also delivered to voltage controlled oscillator 128. The lattergenerates an oscillating signal, the frequency of which varies as afunction of the voltage of the amplified signal provided to voltagecontrolled oscillator 128. This signal is then amplified by amplifier130, and the amplified signal then drives speaker 116 such that thepitch of the sound provided by the speaker 116 varies as a function ofproximity of probe 32′ to marker 30 b. By observing signal meter 126and/or listening to speaker 116, the surgeon can assess when the probe32′ is positioned closest to a selected marker 30 b. Repetition of thisprocess will result in identification of the location of all of markers30 b.

[0107] Turning now to FIGS. 2c, 3 a, 3 b and 8, marker 30 c, whichgenerates an RF signal 44, is identified using probe 32″ and detector34″ in the following manner. RF exciter 60 is operated so as to producean RF exciter signal 46. More particularly, radio frequency generator 62(FIG. 3b) generates a radio frequency signal which is amplified by RFamplifier 64, following sensitivity adjustment using gain adjustment 66,with the amplified signal being provided to antenna 68 for transmissionto markers 30 c. RF exciter 60 is positioned sufficiently close tomarkers 30 c that RF exciter signal 46 is received by antenna 52 of themarkers and is of sufficient strength to drive radio frequency generator56 of the markers. Following detection and regulation by circuit 54(FIG. 3a) of the signal 46 received by antenna 52, radio frequencygenerator 56 generates an RF signal which is transmitted by antenna 52as RF signal 44. Preferably, but not necessarily, each marker 30 ctransmits RF signal 44 at a frequency that is unique to the marker,while an RF exciter signal 46 having a single frequency is preferablyused for all of the markers 30 c, with the frequency of signal 46 beingdifferent than the frequency of signal 44.

[0108] Once exciter 60 has been activated so as to cause marker 30 c togenerate RF signal 44, detection of the marker commences. This isachieved by positioning probe 32″ (FIG. 8) on or adjacent skin 402adjacent tissue volume 22, and then monitoring proximity informationprovided by analog signal strength display 150 and/or speaker 116 ofdetector 34″. More specifically, following receipt of RF signal 44 by,receive antenna 140 of probe 32″, the signal is filtered by selectablenotch filter 142 of probe 32″. By correlating a given marker 30 c, e.g.,marker 30 c, with a corresponding representation on the adjustment knob(not shown) that controls selectable notch filter 142, e.g., thereference number “1,” the surgeon can identify the location of the givenmarker. The knob for adjusting selectable notch filter 142 is shellmoved to a different position when detecting a second marker 30 c, e.g.,marker 30 c ₂.

[0109] Signals from receive antenna 140 that are passed throughselectable notch filter 142 are shell amplified by RF amplifier 144 withthe adjustment of the amplifier gain being provided as needed using gainadjustment 146. The amplified signal is then provided torectifierlintegrator 148 where the signal is rectified and timefiltered. The strength of signal 144 detected by detector 34″ is thendisplayed via analog signal strength display 150 and is provided tovoltage controlled oscillator 152. The latter creates an oscillatingsignal, the frequency of which varies as a function of the voltage ofthe signal provided by rectifier/integrator 148. The output signal fromvoltage controlled oscillator 152 is then amplified by audio amplifier154 and delivered to drive speaker 116. The pitch of the sound providedby speaker 116 will vary as a function of the frequency of the signalprovided by voltage controlled oscillator 152, and as an ultimatefunction of the proximity of probe 32″ to a given marker 30 c. Byobserving the location of probe 32″ when the detection information fromdetector 34″ indicates the probe is closest to a given marker 30 c, thesurgeon can mentally note where the marker is located. By repeating thisprocess for each of the markers 30 c with appropriate adjustment ofselectable notch filter 142, all of the markers 30 c may be located.

[0110] Referring to FIGS. 2d, 3 a, 3 b and 8, marker 30 d may also bedetected using detector 34″ in substantially the same manner discussedabove with respect to marker 30 c. One significant difference, however,is the fact that RF exciter 60 (FIG. 3b) is not used insofar as marker30 d contains its own power source.

[0111] Turning next to FIGS. 2e, 2 f, and 4-6, for makers 30 e and 30 f,which are designed to provide high image contrast when imaged withultrasound, probe 32 includes a conventional ultrasound transducer (notshown) that generates ultrasound in a conventional frequency range,e.g., 7.5 MHz, and receives back reflection of the ultrasound signal.Detector 34 is the image processor and display (neither shown) of aconventional ultrasound apparatus which is connected to the ultrasoundtransducer. Markers 30 e or 30 f are identified by scanning the generalregion of tissue volume 22 with probe 32, and monitoring the ultrasoundimage of the markers provided by detector 34. This ultrasound imagepermits the surgeon to identify the placement of all of the markers, andhence the boundaries of tissue volume 22.

[0112] In the case of marker 30 e, the latter is caused to vibrate at afrequency that is generally significantly less than that of theultrasound generated by the ultrasound transducer in probe 32. Thiscreates, through what is believed to be a Doppler shift phenomenon,enhanced image contrast in the ultrasound signal reflected off markers30 e. Vibration of a marker 30 e is effected by operating RF exciter 92so that radio frequency generator 94 generates a radio frequency signalwhich is amplified by amp 96 and then transmitted by antenna 100.Antenna 80 of marker 30 e receives this RF signal, which is detected andregulated by circuit 84 so as to generate an oscillating electricalsignal that is provided to piezo-electric device 86. This signal causesthe piezo-electric device 86 to mechanically oscillate, whichoscillations are transferred via support 88 to outer housing 90 ofmarker 30 e, thereby causing the housing (and hence the marker) tovibrate.

[0113] Tissue Removal

[0114] Following identification of tissue volume 22 using the proceduresoutlined above, surgical removal of the tissue volume commences.Referring to FIGS. 14 and 16, the first of the two procedures forremoving tissue volume 22 referenced above commences with the formationof an incision 404 (FIG. 14) in skin 402 above tissue volume 22. Thelength of incision 404 is typically about equal to, or slightly greaterthan, the distance between two markers 30 lying on a given axis, e.g.,the Y axis as illustrated in FIG. 14. Next, portions of skin 402adjacent incision 404 are pulled apart by retractors or other knowndevices, so as to form open region 406 (FIG. 16) and expose tissueportion 24 beneath.

[0115] Referring now to FIGS. 11-13 and 17-19, as the next step, tissueanchor 300 is inserted in tissue mass 26 so as to assume the extendedposition illustrated in FIG. 13. This is achieved by inserting a fingerinto ring 302, then pulling rod 304 upwardly (as illustrated in FIG. 12)with respect to cannula 320 so that pin 308 moves in slot 328 toward theend thereof closest to proximal end 324 of the cannula. In thisretracted position, cannula 320 is grasped and is inserted through openregion 406 into tissue volume 22 so that its distal end 326 ispositioned substantially in the center of tissue mass 26. This placementmay be achieved under the guidance of an imaging system (not shown) thatis capable of imaging tissue anchor 300, e.g., ultrasound or X-rayimaging systems. Alternatively, using system 20, the location a marker302 lying beneath tissue volume 22, as illustrated in FIGS. 18 and 19,is identified using the procedure described above to identify the tissuevolume. By identifying the depth at which marker 302 is located andcomparing this to the length of cannula 320 inserted into tissue volume22, distal end 326 may be positioned centrally within tissue mass 26.

[0116] Next, ring 302, and hence rod 304 attached thereto, is forceddownwardly (as viewed in FIG. 17) relative to cannula 320 until pin 308contacts the end of slot 328 closest to distal end 326. As rod 304 moveswithin cannula 320 toward this extended position, anchor members 310 areforced out through apertures 330 and into tissue mass 26 (see FIG. 19).Then, ring 302, and hence rod 304, is rotated slightly so as to causepin 308 to move into pocket 329.

[0117] The next step in the removal of tissue volume 22 is assembly andplacement of cutter 200 in open region 406. Referring to FIGS. 9, 10, 17and 20, cutter portions 202 and 204 are positioned adjacent open region406, as illustrated in FIG. 17. Next, cutter portion 202 is positionedin open region 406, with its curved plate 206 being inserted underportions of skin 402 adjacent the open region, as illustrated in FIG.20. Next, cutter portion 204 is similarly positioned in open region 406.Then, portions 202 and 204 are moved toward one another so that cannula320 of tissue anchor 300 is received in elongate groove 232 in centralhandle section 222 and in elongate groove 255 in central handle section252. Portions 202 and 204 are moved even closer to one another so thatcentral handle sections 222 and 252 engage one another and so thatprojections 258 and 260 are received, respectively, in apertures 228 and230. When positioned in this manner, ends 208 and 210 of curved portion206 of cutter portion 202, engage, respectively, ends 240 and 238 ofcurved portion 236 of cutter portion 204, so as to form a substantiallycontinuous curved cutting edge consisting of cutting edges 212 and 242.Also when positioned in this manner, longitudinal axis 262 of cutter 200extends substantially parallel to the elongate axis of cannula 320, bothof which are substantially co-axial with the Z axis extending throughtissue volume 22. (See FIGS. 18 and 21).

[0118] Next, the position of cutter 200 relative to markers 30 isdetermined by comparing the location of markers, which is typicallydetermined by using probe 32 and detector 34 in the manner describedabove, to the position of the cutter. Then, the location of cutter 200is adjusted so that axis 262 of cutter 200 is substantially co-axialwith Z axis tissue volume 22, as illustrated in FIG. 21. In some casesthe surgeon will recall the location of markers 30 from the prior markeridentification step, and so it will be unnecessary to again locate themarkers. However, when tissue portion 24 is amorphous and pliable, as isthe case when breast tissue is involved, it is recommended that thisalignment of cutter 200 with tissue portions 30 using probe 32 anddetector 34 be performed before any cutting of tissue volume 22commences.

[0119] In connection with the initial insertion of cutter 200 in openportion 406, an appropriately sized cutter 200 is selected such that theradius of curved plates 206 and 236, as measured radially outwardly fromaxis 262, is substantially the same as the radius of tissue volume 22 asmeasured radially outward from the Z axis. While this relationshipbetween the radii of curved plates 206 and 236 of cutter 200 and theradius of tissue volume 22 as measured with respect to Z axis, ispreferred, in some cases it may be satisfactory to use a cutter having aradius that is greater than or less than the radius of the tissue volume22. Also, the height of curved portions 206 and 236 is another factorconsidered in selecting an appropriate cutter 200.

[0120] Referring to FIGS. 18-22, as the next step in the removal oftissue volume 22, ring 302 of tissue anchor 300 is typically pulledupwardly in the direction of arrow F (see FIGS. 19 and 21) sufficientlyto tension tissue volume 22 and adjacent portions of tissue portion 24.By this tensioning of tissue volume 22 and tissue portion 24 thetendency of the tissue portion to compress under the force of a cuttingdevice is reduced. Also, this tensioning of tissue volume 22 serves tostabilize the tissue volume during the surgical removal process.

[0121] In some cases, sufficient tissue stabilization can be achievedmerely by holding tissue anchor 300 in a substantially fixed positionrelative to tissue volume 22. In other words, no force in the directionof arrow F is applied to tissue anchor 300 except as may be necessary tohold the tissue anchor in a stable position.

[0122] Then, while stabilizing tissue volume 22 with tissue anchor 300,preferably, but not necessarily by maintaining an upward force on thetissue anchor, the surgeon grips handles 220 and 250 of cutter 200 andbegins pressing downwardly on the handles toward tissue volume 22, i.e.,in the direction of arrow D (see FIG. 21). At the same time, handles 220and 250 are rotated about cutter axis 262 in either or both a clockwiseand counterclockwise direction, i.e., in the direction indicated bycurved arrow R (see FIG. 21). Elongate grooves 232 and 255 are sized topermit cutter 200 to rotate relatively freely about cannula 320positioned therein. Pins 258 and 260 and associated apertures 228 and230 are provided to ensure portions 202 and 204 remain operativelyengaged with one another as illustrated in FIG. 10, and so that theportions rotate together when a rotational force is applied to one ofthe portions.

[0123] As cutter 200 is rotated about its axis 262 and is urgeddownwardly towards tissue volume 22, bottom edges 212 and 242 begincutting tissue volume 22 along its outer boundary. Progress in removingtissue volume 22 is generally periodically determined by comparing theposition of curve plates 206 and 236 of cutter 200 relative to markers30 using probe 32 and detector 34 to identify the locations of markers30 and then comparing such locations with the location of the cutter. Inparticular, a determination can be made as to when tissue volume 22 hasbeen severed from tissue portion 24 to a depth defined by marker 302(FIG. 21) defining the bottom or innermost portion of the tissue volume.Thus, by iteratively comparing the position of cutter 200 to thelocations of markers 30 using marker location information acquired fromdetector 34 based on proximity information provided by the detector, asurgeon can determine when the cutting operation is completed and cutter200 can be removed from tissue portion 24, as indicated in FIG. 22.

[0124] Depending upon the size of cutter 200 relative to the placementof markers 30, the latter may remain in place in tissue portion 24following removal of tissue volume 22, as indicated in FIG. 22. If suchas the case, markers 30 are then subsequently removed by first locatingthe markers using probe 32 and detector 34 and then removing the markerswith a suitable instrument, e.g., tweezers. In other cases, the markerswill be included in the tissue volume 22.

[0125] In some cases, it will be necessary to sever the bottom orinnermost portion of tissue volume 22 from tissue portion 24 so as topermit removal of the tissue volume. A scalpel or other conventionaltool may be used to perform this final severing of the tissue volume.The precise location where this final incision is made may be determinedby again locating the position of marker 302 using probe 32 and detector34. By leaning tissue anchor 300 and cutter 200 to one side, a surgeoncan typically follow the incision created by cutter 200 with a scalpelor other tool down to the region where marker 302 is located and tissuevolume 22 remains attached to tissue portion 24.

[0126] As noted above, in some circumstances a marker 302 is notrequired when the bottom or innermost portion of tissue volume 22 ispositioned immediately above a different type of tissue, e.g., apectoral muscle 400. In such case, the surgeon can assess when cutter200 has been inserted sufficiently deep into tissue portion 24 by merelyobserving when bottom cutting edges 212 and 242 are about to engage thedifferent type of tissue.

[0127] Referring to FIG. 1a, by inserting markers 30 at staggeredlocations along the Z axis, the relative depth of cutter 200 in tissueportion 24 can be determined by locating specific markers using probe 32and detector 34. The location of such markers 30 is then compared withthe location of cutter 200 to determine the depth of the cut. Forexample, if markers 30 c are installed at positions X₁ and X₂ in FIG.1a, and each marker has a unique frequency, these markers can beuniquely identified by detector 34″ (FIG. 8) in the manner describedabove.

[0128] Referring to FIG. 1b, by positioning more than four markers,e.g., eight markers as illustrated in FIG. 1b, the boundaries of tissuevolume 22 can often be more readily defined during the removal of thetissue volume. This is so because increasing the number of markers 30used increases the quantity of information received from detector 34regarding the boundaries of tissue volume 22.

[0129] While the use of cutter 200 in connection with the removal tissuevolume 22 often expedites removal of the tissue volume, use of thecutter is not a mandatory aspect of the present method of bracketing andremoving the tissue volume. In this regard, a conventional scalpel mayoften be satisfactorily employed in place of cutter 200. Also, undercertain circumstances it may be desirable to initiate an incision withcutter 200, and then complete the incision with a scalpel.

[0130] The process of removing tissue volume 22 using a scalpel alsopreferably commences by inserting tissue anchor 300 in tissue volume 22in the manner described above. The location of markers 30 are alsodetermined prior to and during the removal of tissue volume 22 byscalpel in the manner described above. Thus, during the removal oftissue volume 22, the boundaries thereof may be repeatedly identified bylocating markers 30 using probe 32 and detector 34. As noted above, itis generally advantageous to use tissue anchor 300 when removing tissuevolume 22 with a scalpel because by stabilizing the tissue volume andsurrounding regions of tissue portion 24, it is easier to maintainalignment of the scalpel with the boundaries of the tissue volume.However, it is to be appreciated that the use of tissue anchor 300 is apreferred, but not essential, aspect of the present method of bracketingand removing tissue volume 22.

[0131] Referring now to FIG. 2g and FIG. 15, as noted above, probe 32and detector 34 are not used in connection with marker 30 g. Thedetection characteristic of markers 30g is the release of a colored dye78 in surgical cavity adjacent the markers. Removal of a tissue volume22 bracketed by markers 30 g differs from the removal of tissue volumewhen bracketed by the other embodiments of marker 30 in that thelocation of marker 30 g is not determined by the surgeon prior toinitiation of the removal of tissue volume 22. Practically speaking,this is more a difference in the process for removing tissue volume 22than a difference in the composition and construction of marker 30 g.This is so because for implantation purposes, marker 30 g mustnecessarily be imagable by some form of imaging system, which imagingsystem could, in most cases, also be used by the surgeon to identify thelocation of marker 30 g prior to and in connection with the removal oftissue volume 22. For example, if marker 30 g is initially implanted byimaging the marker using an ultrasound system, then marker 30 g isactually a marker 30 f. Thus, in connection with the followingdescription of the process of removing tissue volume 22 bracketed withmarkers 30 g, it is assumed the markers are not located by the surgeonprior to, or in connection with, the removal of tissue volume other thanby visual observation, as discussed below.

[0132] Removal of tissue volume 22 bracketed by markers 30 g alsopreferably commences by installing tissue anchor 300 as described above.Again, the use of tissue anchor 300 is preferred, but not mandatory.Next, the surgeon commences cutting the general region of tissue volume22, which can be defined by colored marks, Kopanz needles or other knowntechniques. Then, the removal of tissue volume 22 proceeds using eithercutter 200, or a scalpel or other cutting device, as described above. Asthis removal of tissue volume 22 is performed, tissue anchor 300, ifused, is manipulated to stabilize tissue volume 22 in the mannerdescribed above. As cutter 200, the scalpel or other cutting deviceencounters a marker 30 g, the capsule of the marker is severed releasingthe colored dye 78. This advises the surgeon that a boundary of tissuevolume 22 has been encountered. It may be advantageous to use a givencolor of dye in markers 30 g defining one side of the boundary of tissuevolume 22, while the markers 30 g defining an opposite side include adifferent color of dye. By defining the boundary of tissue volume 22with a sufficient number, e.g., 10-25, of markers 30 g, the boundary) oftissue volume 22 can typically be identified by iteratively cutting andobserving whether dye appears in the surgical cavity.

[0133] As noted above, marker embodiments 30 a-30 f may all includecolored dye 78 within an outer capsule that is sufficiently tough towithstand insertion and yet is relatively easily cut by cutter 200, ascalpel or other cutting device. Such use of dye in markers 30 providesanother source of information for the surgeon regarding the boundary oftissue volume 22.

[0134] An important advantage of tissue bracketing system 20 is that ispermits the relatively precise identification of the boundaries oftissue volume 22 without the need for needles, wires or other cumbersomeapparatus projecting from tissue portion 24. As such, bracketing systempermits a surgeon to relatively quickly and easily identify the tissueboundary of tissue volume 22 and remove the tissue volume. In addition,system 20 is ideally adopted for bracketing a tissue volume 22 inamorphous, pliable tissue, such as breast tissue.

[0135] An important advantage of cutter 200 is that it permits a tissuevolume 22 of relatively large diameter to be removed through arelatively small incision 404. This advantage is important in this erawhen tissue-conserving therapies are being emphasized.

[0136] By stabilizing tissue volume 22 Using tissue anchor 300, theaccuracy with which a surgeon can remove tissue volume 22 is enhanced.This advantage of the present invention arises because tensioning of thetissue volume 22 by pulling upwardly on tissue anchor 300 serves toretain the tissue portion in a relatively stable position. Indeed, evenholding tissue anchor 300 in a substantially fixed position relative tothe tissue volume 22 with which it is engaged typically providesbeneficial stabilization of the tissue volume.

[0137] While cutter 200 and tissue anchor 300 may be advantageouslyemployed in connection with the present method of bracketing andremoving tissue volume 22, it is to be appreciated that the cutter andtissue anchor have application in many other contexts. Morespecifically, in any application in which it is desired to remove avolume of tissue through as small an incision as possible, cutter 200has important utility. Similarly, when is desired to stabilize a pieceof tissue in connection with surgical removal or other treatment of thepiece of tissue, whether or not within the bracketing context of thepresent invention, tissue anchor 300 also has important application.

[0138] Since certain changes may be made in the above apparatus andprocesses without departing from the scope of the present invention, itis intended that all matter contained in the preceding description orshown in the accompanying drawings shall be interpreted in anillustrative and not in a limiting sense.

I/we claim:
 1. A system for bracketing a tissue volume comprising: a. a plurality of markers, each marker in said plurality having a maximum dimension of no more than 5 mm, as measured along any axis extending through said each marker; b. a probe; and c. a detector connected to said probe that provides information when said probe is moved proximate to one of said plurality of markers.
 2. A system according to claim 1, wherein said maximum dimension is no more than 2 mm.
 3. A system according to claim 1, wherein said detector further includes at least one selected from the group consisting of a sound source, a light source, a source of pressurized air, a display for providing changing proximity information, a dial with a movable needle, and a display for displaying an image.
 4. A system according to claim 3, wherein said information is at least one of sound, light, pressurized air, visually represented proximity information, movement of a needle, and an image on a display that is provided, respectively, by said sound source, said light source, said source of pressurized air, said display for providing changing proximity information, said dial and said display for displaying an image.
 5. A system according to claim 1, wherein said detector provides said information so that an attribute thereof varies as a function of proximity of said probe to individual markers in said plurality of markers.
 6. A system according to claim 1, wherein at least one of said plurality of markers emits gamma rays.
 7. A system according to claim 1, wherein at least one of said plurality of markers generates a magnetic field.
 8. A system according to claim 1, wherein at least one of said plurality of markers generates a radio frequency signal.
 9. A system according to claim 1, wherein at least one of said plurality of markers includes: a. an antenna; and b. a radio frequency generator connected to said antenna for generating a first radio frequency signal having a first frequency for transmission by said antenna.
 10. A system according to claim 9, further including a circuit connected to said antenna for detecting and regulating an exciter signal received by said antenna, wherein said radio frequency generator is designed to generate said first radio frequency signal using energy in said exciter signal.
 11. A system according to claim 10, further including an exciter for generating said exciter signal.
 12. A system according to claim 1, wherein each of said plurality of markers includes: a. an antenna; b. a circuit connected to said antenna for generating a radio frequency signal, in response to receipt of an exciter signal, having a frequency that is different from frequencies of said radio frequency signals generated by other ones of said plurality of markers; and c. an exciter for generating said exciter signal, wherein said exciter signal does not include a radio frequency signal having a frequency that is the same as frequencies of said radio frequency signals generated by said plurality of markers.
 13. A system according to claim 1, wherein at least one of said plurality of markers vibrates.
 14. A system according to claim 1, wherein at least one of said plurality of markers includes: a. a piezo-electric device that oscillates mechanically in response to an oscillating electrical signal; and b. a circuit connected to said piezo-electric device that generates said oscillating electrical signal.
 15. A system according to claim 14, wherein said at least one of said plurality of markers has a housing that is designed to resonate at a first frequency and said piezo-electric device is coupled to said housing so that mechanical oscillations of said piezo-electric device are transmitted from said piezo-electric device to said housing.
 16. A system according to claim 14, wherein said at least one of said plurality of markers includes: a. an antenna for receiving an exciter signal; b. wherein said circuit is connected to said antenna and is designed to generate said oscillating electrical signal when said antenna receives said exciter signal; and c. an exciter for generating said exciter signal.
 17. A system according to claim 1, wherein at least one of said plurality of markers includes a plurality of plates that are configured, positioned and made from a material such that said at least one marker strongly reflects ultrasound energy incident thereon.
 18. A system according to claim 1, wherein at least one of said plurality of markers is designed to reflect ultrasound energy incident thereon.
 19. A system according to claim 1, wherein at least one of said plurality of markers includes a capsule filled with a colored dye.
 20. A system for bracketing a tissue mass comprising: a. a plurality of markers, each having a detection characteristic; b. a probe; and c. a detector that detects said detection characteristic and provides a humanly recognizable representation of proximity of said probe to one of said plurality of markers that varies as a function of changes in said proximity.
 21. A system according to claim 20, wherein said detection characteristic is gamma rays.
 22. A system according to claim 20, wherein said detection characteristic is a magnetic field.
 23. A system according to claim 20, wherein said detection characteristic is radio frequency electromagnetic energy.
 24. A system according to claim 20, wherein said detection characteristic is imagability by ultrasound energy.
 25. A system according to claim 20, wherein said detector includes a sensor that determines the strength of said detection characteristic and generates an output signal having a magnitude that varies as a function of the strength of said detection characteristic, as determined at said probe.
 26. A surgical marker comprising: a. a quantity of colored dye; b. a capsule encasing said quantity of colored dye; and c. wherein at least one of said dye and capsule is imagable by at least one of ultrasonic, magnetic resonance and X-ray energy.
 27. A surgical marker according to claim 26, wherein said capsule has a maximum dimension of no more than 5 mm, as measured along any axis extending through said capsule.
 28. A cutting tool comprising: a. a first portion including: i. a first blade having a first edge with a first curved configuration; ii. a first connector; b. a second portion including: i. a second blade having a second edge, wherein said second edge has a second curved configuration that is designed so that when said second blade is positioned in operative engagement with said first blade, said first edge and said second edge form a substantially continuous cutting edge; ii. a second connector positioned and designed to releasably engage said first connector so as to releasably secure said second blade in said operative engagement with said first blade.
 29. A cutting tool according to claim 28, wherein said first curved configuration and said second curved configuration are selected so that said substantially continuous cutting edge is circular.
 30. A cutting tool according to claim 28, further wherein said first portion has a first handle and said second portion has a second handle.
 31. A cutting tool according to claim 30, wherein said first connector is attached to said first handle and said second connector is attached to said second handle.
 32. A tissue anchor comprising: a. an elongate tube having a central bore, a distal end and a proximal end, wherein said tube has at least one aperture adjacent said distal end; b. an elongate member having a portion sized for receipt and axial movement in said central bore between a first position and a second position, wherein said elongate member includes a longitudinal axis and at least one anchor member attached to said portion; and c. wherein said at least one anchor member is configured and positioned so that when said portion is in said first position said at least one anchor member is at least partially received in said elongate tube and when said portion is in said second position said at least one anchor member projects through said at least one aperture and extends transversely relative to said longitudinal axis.
 33. A tissue anchor according to claim 32, further wherein said elongate tube has an outside diameter ranging 0.5 mm to 12 mm.
 34. A tissue anchor according to claim 32, wherein said outside diameter ranges from 0.1 mm to 3 mm.
 35. A tissue anchor according to claim 32, wherein said at least one anchor member includes four anchor members.
 36. A tissue anchor according to claim 32, wherein said at least one anchor member has a curved configuration when said portion is in said second position.
 37. A system for bracketing, stabilizing and removing a tissue volume comprising: a. a marker system including: i. a plurality of markers, each marker in said plurality having a maximum dimension of no more than 5 mm, as measured along any axis extending through said each marker; ii. a probe; and iii. a detector connected to said probe that provides information when said probe is moved proximate to one of said plurality of markers; b. a cutter including: i. a first portion having: (1) a first blade having a first edge with a first curved configuration; (2) a first connector; ii. a second portion having: (1) a second blade having a second edge, wherein said second edge has a second curved configuration that is designed so that when said second blade is positioned in operative engagement with said first blade, said first edge and said second edge form a substantially continuous cutting edge; (2) a second connector positioned and designed to releasably engage said first connector to releasably secure said second blade in said operative engagement with said first blade; and c. a tissue anchor including: i. an elongate tube having a central bore, a distal end and a proximal end, wherein said tube has at least one aperture adjacent said distal end; ii. an elongate member having a portion sized for receipt and axial movement in said central bore between a first position and a second position, wherein said elongate member includes a longitudinal axis and at least one anchor member attached to said portion; and iii. wherein said at least one anchor member is configured and positioned so that when said portion is in said first position said at least one anchor member is at least partially received in said elongate tube and when said portion is in said second position said at least one anchor member projects through said at least one aperture and extends transversely relative to said longitudinal axis.
 38. A method of removing a tissue volume from a tissue portion using a plurality of markers, the method comprising the steps: a. positioning a plurality of markers so as to define a boundary of the tissue volume; b. detecting the location of a first one of the plurality of markers; and c. incising portions of the tissue portion adjacent said first one of the plurality of markers substantially along said boundary adjacent said location.
 39. A method according to claim 38, wherein said positioning step is performed so that said plurality of markers define said boundary in three dimensions.
 40. A method according to claim 38, wherein said positioning step is performed so that said plurality of markers define said boundary in two dimensions.
 41. A method according to claim 38, wherein said positioning step is performed so that said plurality of markers define said boundary in one dimension.
 42. A method according to claim 38, wherein said positioning step involves positioning the plurality of markers using ultrasound imaging to guide placement of the plurality of markers.
 43. A method according to claim 38, wherein said positioning step involves positioning the plurality of markers using X-ray imaging to guide placement of the plurality of markers.
 44. A method according to claim 38, wherein said positioning step involves positioning the plurality of markers using magnetic resonance imaging to guide placement of the plurality of markers.
 45. A method according to claim 38, wherein said positioning step involves positioning the plurality of markers using CAT-scan imaging to guide placement of the plurality of markers.
 46. A method according to claim 38, wherein the plurality of markers includes three pairs of markers, further wherein said positioning step involves positioning the three pairs of markers so that markers of each pair lie on said boundary in mutually spaced relation substantially on opposite sides of the tissue volume.
 47. A method according to claim 38, wherein said positioning step involves positioning said plurality of markers so that at least two of said plurality of markers lie on an X axis and at least two of said plurality of markers lie on a Y axis, wherein said X axis and said Y axis intersect said tissue volume and extend in non-coaxial relation.
 48. A method according to claim 38, further including the steps of repeating said detecting step and said incising step with respect to other ones of the plurality of markers.
 49. A method according to claim 38, further including the steps of repeating said detecting step and said incising step with respect to all of said plurality of markers until the tissue volume is separated from the tissue portion.
 50. A method according to claim 38, further comprising the step, before said positioning step, of identifying a tissue mass located in the tissue volume.
 51. A method of removing a tissue volume comprising the steps: a. forming an incision in skin covering the tissue volume; b. providing a cutter having a first portion and a second portion, wherein said first portion and said second portion are designed to be attached together in operative engagement, said cutter having a cutting edge for cutting the tissue volume; c. inserting said first portion through said incision; d. inserting said second portion through said incision and attaching said first portion to said second portion so as to create said operative engagement; and e. applying a rotational force and a downward force toward the tissue volume to said cutter so as to cause said cutting edge to cut the tissue volume.
 52. A method according to claim 51, further comprising the step, prior to said step b, of positioning a plurality of markers so as to define a boundary of the tissue volume and the step, after said step d and before said step e, of identifying said boundary by detecting the position of said plurality of markers and then positioning said cutter in alignment with said boundary.
 53. A method of bracketing a tissue mass in a piece of tissue using a plurality of markers, the method comprising the steps: a. generating an image of the tissue mass; and b. referring to said image of the tissue mass, positioning the plurality of markers in the piece of tissue so as to define a boundary of a tissue volume that includes the tissue mass.
 54. A method according to claim 53, further comprises the step after said step a and before said step b of positioning the plurality of markers proximate the tissue mass and generating an image of the plurality of markers, further wherein said step b involves referring to said image of the plurality of markers in connection with said positioning.
 55. A method according to claim 53, wherein said step b involves positioning the plurality of markers so that two of said plurality of markers are positioned on an X axis, two of said plurality of markers are positioned on a Y axis and two of said plurality of markers are positioned on a Z axes, said X, Y and Z axes intersecting the tissue volume and extending in non-coplanar relation.
 56. A method according to claim 53, wherein said step b involves positioning the plurality of markers so that said X, Y and Z axes are substantially mutual orthogonal.
 57. A method according to claim 53, wherein said step b is performed so that the plurality of markers defines said boundary in one dimension.
 58. A method according to claim 53, wherein said step b is performed so that the plurality of markers defines said boundary in two dimensions.
 59. A method according to claim 53, wherein said step b is performed so that the plurality of markers defines said boundary in three dimensions.
 60. A method according to claim 53, wherein said step b is performed so that said at least two of the plurality of markers are positioned on an X₁ axis and at least two of the plurality of markers are positioned on a Y₁ axis, wherein said X₁ axis and said Y₁ axis are offset along said Z axis, respectively, from said X axis and said Y axis.
 61. A method of removing a tissue mass and surrounding tissue volume from a piece of tissue, the method comprising the steps: a. positioning a plurality of markers in the piece of tissue so as to define a boundary of the tissue volume; b. identifying said boundary by detecting the position of said plurality of markers; c. incising portions of said tissue volume adjacent said plurality of markers substantially along said boundary based on said position of said plurality of markers; and d. stabilizing the tissue volume during said incising step.
 62. A method according to claim 61, wherein said identifying step and said incising step are repeated until said tissue volume is removed from the piece of tissue.
 63. A method according to claim 61, wherein said incising step is performed so that said incising extends in a second direction that is different than said first direction.
 64. A method according to claim 61, wherein said stabilizing step involves pulling the tissue volume in a first direction. 